Back spacing for rear 69 camaro/firebird with mini tub?

[jlwdvm]

Trying to get a set of Vinatage Wheel Works V40's ordered for my 69 firebird TA track car clone. Looks like 18x9.5 with 6" back spacing is going to be a safe bet for the front with 275 Toyo R888s and Ride Tech Tru Turn (may have to use a spacer to get it dialed in exactly) and I will be using 18x11 for my 315 Toyo R888s for the rear. The car is mini tubbed and I am wondering what back spacing I should get for the rear. I will be using a Ride Tech 4-link for the rear mounted from the leaf spring perches on the rear so I can't narrow the rear too much. I will probably be ordering a Currie 9". I don't want too much dish on the rears either. Any ideas for the rear back spacing? I'm gonna order the rear end after I get final measurements with the wheel-tire combo under the car.
https://static1.pt-content.com/images/pt/2014/03/69move002_zpsad213888-1.jpg (http://s1258.photobucket.com/user/jlwdvm/media/69move002_zpsad213888.jpg.html)

[cwylie]

If I were to do it all over again I would have left my rear axle stock width or really close to it. My axle is 54 inches from mounting surface to mounting surface and I ordered 18x12 with 5.5 backspace and now I have to run a 7/8ths spacer as they were tucked too far in. Every car will be difference, I would rent the tool and measure on your car. I wish I would have rented or bought a wheel fitment tool.

[jlwdvm]

I've been following your progress since we are basically running the same suspension. If my math is correct and I went with a stock rear width (60" wms-wms) then I would need 7.5" of back space with a 12" rim. This takes into consideration adding 3" to each side for wms, removing basically 1" from yours (so I wouldn't need a spacer). So if I am using an 11" rim, would I just remove 1/2" from each side of the rim centerline to get 7" backspace? Sound right? I'm ordering my wheels and tires before the rear so I can adjust the width of the rear if needed.

[cwylie]

Yeah I think its a good idea to order wheels first. Honestly I would figure out how much lip you what on the rear wheel and what brakes you are going to run and go from there. Depending on what wheel company you go with and wheel style they are can be limited on the backspace specs. I went with CCW and they could have built a wheel a 18x12 with 4.5 inches of backspace but it would have been with a lot more pad height than I wanted. My WMS to WMS is actually closer to 54.5 once I have the brake rotors on. I will get an exact measurement on the thickness of my rotors for you.

[jlwdvm]

After much research, head scratching, and re-reading the Tru Turn thread on Lat G 3-4 times I finally ordered V40 rims...18x9.5" with 6" back spacing for the front and 18x11 with 7" for the rear. Hopefully that gets me close at both ends of the car, but I guess I can always use a spacer if needed. That's why I erred on the side of having a little too much back spacing, rather than not enough.